Development Of Two Kinds Of Detectors In Preparation Of Pulse Squeezed State

As a very important quantum resource,due to the characteristics of breaking through the standard quantum limit,squeezed states have great potential in the fields of quantum communication,quantum precision measurement and quantum imaging,especially in the field of optical microscopy.The recently squeezed state is used in a microscopic imaging system based on stimulated Raman scattering,which realizes quantum enhanced nonlinear microscopic imaging.The signal-to-noise ratio is effectively improved without increasing the incident power of the sample,which provides a new way to improve the imaging rate and imaging resolution.At present,most of the high-compression squeezed states are prepared under continuous light source.However,due to the high peak power characteristics of pulsed laser,it becomes an ideal choice for stimulated Raman scattering microscopic imaging.In order to obtain a high-compression squeezed state experimentally,in addition to requiring a highquality generation device,it is necessary to have a high-performance photoelectric detection device.The balanced homodyne detection that can reduce the classical noise has become the best choice.Therefore,the development of balanced homodyne detectors with low noise,high bandwidth,high signal-to-noise ratio and high common-mode rejection ratio is an important guarantee for the preparation of high-compression squeezed states.However,the high power of the pulse laser at the repetition frequency will lead to premature saturation of the detector.The experiment needs to consider the lower frequency of the pulse light and the influence of the repetition frequency on the detection of the stimulated Raman scattering signal light.The resonant detector has the characteristics of narrow bandwidth and high gain at the resonant frequency.At the same time,it can suppress the interference of non-resonant frequency and realize the detection of high signal-to-noise ratio of the required signal light.The main tasks of this paper include:1.Combining the advantages of balanced homodyne detection and resonant circuit,a20 MHz resonant balanced homodyne detector is developed.The resonant frequency of the detector is far away from the low-frequency laser noise and electronic noise that have a great influence on the detection of squeezed states,and forms a consistent periodic mode with the 80 MHz repetition frequency of the pulsed light.The linearity of the detector was experimentally detected under a continuous light source,and a signal-to-noise ratio of 22.42 d B was obtained.Under the pulsed light source,a signal-to-noise ratio of 10.02 d B is obtained,and the interference of the 80 MHz repetition rate of the pulsed laser is suppressed.The detector will be used in the next research work of quantum enhanced nonlinear microscopy.2.Using the developed 20 MHz resonant balanced homodyne detector,the phase noise of the pulsed vacuum squeezed state with a wavelength of 1031 nm,a repetition rate of 80 MHz and a pulse width of 2 ps was measured,and a compression degree of 1.7 d B was obtained at 20 MHz.3.A 100 MHz broadband balanced homodyne detector was fabricated.All the edge distributions of the pulse vacuum state with a wavelength of 1031 nm,a repetition frequency of 80 MHz and a pulse width of 2 ps are measured in time domain.The Wigner function of the vacuum state is reconstructed by quantum tomography,and the fidelity of 98% is obtained.The detector will be used to measure the broadband pulse squeezed state,which is prepared for the next step of measuring the non-classical state in time domain and reconstructing the Wigner function of the measured state.